Because of its Earth-like features and
position in the habitable zone of a Sun-like star Kepler-452b also referred to
as Earth 2.0 or Earth’s Cousin has drawn the attention of scientists, researchers
and space enthusiasts alike. It is the sole planet in the Kepler-452 system as
of right now having been found by NASAs
Kepler Space Telescope. There are good chances to make this exoplanet
habitable and there may be heated debates about whether it could sustain life.
Although it is generally accepted as a verified exoplanet a 2018 study by Mullally et al. argued
that Kepler-452b should be regarded as a candidate planet (planets that require
scientific confirmation and compelling evidence to be proven of their
existence) even though its existence has not been statistically confirmed. It
is still a serious contender for planetary status though as it has not been
demonstrated to be a false positive.
A World at a Distance.
Situated in the constellation Cygnus, some 1800 light-years (550 parsecs)
away from Earth Kepler-452b revolves around its star Kepler-452 at a distance
of 1. 04 AU which is nearly the same
as the distance between Earth and the Sun (156
million km or 97 million miles). Its orbital period is approximately 385 Earth days which is very similar to
the length of a year. For the purpose of researching possibly habitable worlds
outside of our solar system Kepler-452b is an intriguing candidate.
Nevertheless the trip to Kepler-452b is extremely far away even though it is
similar to Earth. It would take roughly 30
million years to reach this far-off exoplanet if it were to travel at the
speed of NASAs New Horizons spacecraft which is roughly 59000 km/h (16000 m/s/37000 mph). This
emphasizes how difficult it is to study such distant worlds and why probes
cannot yet be sent there by current technologies potentially turning them into
second Earths.
A Super-Earth in the Zone of Habitability.
Super-Earths which are exoplanets bigger
than Earth but smaller than gas giants like Jupiter and Neptune are what
Kepler-452b is categorized as. It is twice as large as Earth with a radius that
is roughly 1.6 times that of Earth.
Because of its roughly five times the
mass of Earth the planet's surface gravity is almost twice as strong as
Earth's.
Comparison of the sizes of Earth (left) and
Kepler-452b (right) as well as the parent stars similarities.
Kepler-452b is a super-Earth planet that
is 60% bigger than Earth and orbits
within the habitable zone of its star which may contain liquid water.
Physically if Kepler-452b is rocky it may have active volcanoes and a strong
gravitational pull due to its greater mass and density.
It
is estimated to have a mass five times that of Earth and a surface gravity that
is almost twice as high as ours. It is believed to have a dense overcast
atmosphere that could make it difficult to see the surface. Climate and
temperature: The planet is marginally warmer than Earth with an equilibrium temperature of about 265 K (-8
°C 17 °F). Despite receiving roughly 10%
more stellar energy than Earth which could lead to a runaway greenhouse
effect, its greater mass may help it keep its oceans for a longer period of
time. Kepler-452b is in orbit around a
G2-type star that resembles our Sun. It orbits at a distance similar to
Earth's from the Sun and its year lasts 385 Earth days. Comparatively speaking
the host star is roughly 1. 5 billion
years older than our Sun. Potential for habitability .The planet's long
history (more than 6 billion years) and location in the habitable zone make it
conducive to life. Its habitability is still unknown though due to significant
uncertainties in its composition, mass and atmospheric dynamics.
Challenges for observation: Kepler-452b is too
far away—1800 light-years—for modern
telescopes to determine its precise mass or examine its atmosphere. More
information may be available from upcoming telescopes like the James Web
Space Telescope.
Kepler-452
: The Host Star
The host star is Kepler-452. Kepler-452b
is hosted by Kepler-452, a G-type star
with many similarities to our Sun. It is about 11% bigger and 3.7% more massive
than the Sun and because of these features Kepler-452 is a perfect candidate
for planets that resemble Earth. Its surface temperature of 5757 K is nearly equal to the Sun's 5778 K. These characteristics make
Kepler-452 an ideal candidate for Earth-like planets. Because of its roughly 20% higher luminosity than the Sun any
planets in its habitable zone receive a little bit more energy. With an
estimated age of 6 billion years the star is 15. 5 billion years older than the Sun which is roughly 4. 6 billion years old. The age of
Kepler-452 is important because it suggests that any planets in its orbit such
as Kepler-452b have had billions of years.
The development of intricate biological
systems depends on this prolonged period of time. The Sun would appear almost
the same from Kepler-452bs surface as it does from Earth albeit a little
fainter because of its greater distance. However Kepler-452 is too faint to be
seen with the naked eye with an apparent magnitude
of 13.4.
The distance of Kepler-452b from its star is 1. 04 AU and it completes one orbit
every 385 days which is strikingly
comparable to an Earth year. Since its orbit is thought to be round and not
tidally locked, planets may rotate and experience day-night cycles that
resemble those of Earth. Unlike tidally locked planets where one side is always
facing the star this would be significant for any kind of life because the
planet could undergo regular changes in temperature and environmental
conditions.
An illustration showing Kepler-452bs
orbit within the Kepler-452 system in relation to the inner Solar System and
the Kepler-186 system along with the
area that is predicted to be habitable for each. Kepler-452bs orbit and
proximity to its star place are in a delicate balance despite the fact that it
resembles Earth.
Conclusion
One
of the most intriguing exoplanets discovered in recent years is Kepler-452b
which is similar to Earth and lies in the habitable zone of its star. Although
the planet's habitability is still unknown it remains an important research
topic especially given the risks of a runaway
greenhouse effect. Kepler-452b marks a major turning point in the hunt for
extrasolar life as the first possibly rocky super-Earth found in the habitable
zone of a Sun-like star. Although there is still much to learn about the true
nature of this exoplanet it may one day provide invaluable insights into the
conditions that make a planet suitable for life.
NAME - Mythili M Kulkarni
BATCH NO. - 28